1. Technical Field
The present invention generally relates to third generation mobile system (3GPP) GSM/GPRS/EDGE wireless devices.
It finds applications, in particular, in Dual Subscriber Identity Module (SIM) products in Dual Standby mode (DSDS) and more generally in products comprising a plurality of Subscriber Identities.
2. Related Art
The approaches described in this section could be pursued, but are not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
With DSDS architecture, when one SIM of a mobile phone is in communication, for example during a call or exchange of data, a high rate of network reception level is lost on the second SIM during mobility.
In this case, after the communication on the first SIM releases, several tens of seconds are necessary for the second SIM to camp back on the network and to be able to answer to a Mobile Terminated call (MT call) or to initiate a Mobile Originated call (MO call).
When one SIM responds to an entering communication, only reception power level monitoring and frequency and timing synchronization block decoding of the second SIM serving cells and neighbouring cells, which are selected before the entering communication is received, are possible. In what follows, FCH stands for frequency channel and SCH stands for synchronization channel.
Other activities are not permitted on the second SIM, thus resulting in a de-synchronization with Home Public Land Mobile Network (HPLMN), i.e. the network corresponding to a SIM operator, or with equivalent Public Land Mobile Network (PLMN), in some use cases such as roaming or limited service.
Thus, there is a need to quickly be able to initiate a MO call or to answer to a MT call on the second SIM after the first SIM communication release.